Pump impeller making

ABSTRACT

The process of making an impeller for use in a pump by affixing a disc having blades formed about its outer periphery onto the reduced diameter portion of a hub. A plurality of longitudinal grooves is formed lengthwise into the reduced diameter hub portion and then pressed into a circular bore formed in the center of the impeller disc. The assembly is then placed in a press to swage the outer annular edge of the reduced diameter hub portion into a chafer provided around the circular bore of the disc to thereby solidly hold the disk against the shoulder on the hub.

y 22, 1973 1.. J. SIEGHARTNER 3,734,697

PUMP IMPELLER MAKING Filed July 13, 1970 2 j w m M w fl 2 a. 1 m 3 m a. w NW g fwd w w United States Patent O US. Cl. 29156.8 R 3 Claims ABSTRACT OF THE DISCLOSURE The process of making an impeller for use in a pump by affixing a disc having blades formed about its outer periphery onto the reduced diameter portion of a hub. A plurality of longitudinal grooves is formed lengthwise into the reduced diameter hub portion and then pressed into a circular bore formed in the center of the impeller disc. The assembly is then placed in a press to swage the outer annular edge of the reduced diameter hub portion into a chamfer provided around the circular bore of the disc to thereby solidly hold the disc against the shoulder on the hub.

BACKGROUND OF THE INVENTION This invention relates to a pump impeller design and in particular, relates to a method of making a pump impeller.

In order to meet the varied capacity and head requirements for regenerative turbine pumps, it is necessary to have a multitude of impeller diameters and thicknesses to accommodate a series of pumps. Also, in the design of different pumps mechanical considerations dictate that the hubs be of different sizes even though the impeller disc portions have identical dimensions. Using current techniques of making pump impellers, it requires the machining and stocking of a large inventory of impellers of various sizes. This invention avoids the necessity of maintaining such a large inventory by providing a method of mounting different size discs having peripheral impeller blades onto different size hubs in a quick operation.

SUMMARY OF THE INVENTION This invention provides a method for affixing a disc having impeller blades formed about its periphery onto a hub in a fast and economical manner. Prior to mounting the impeller disc on the hub, a straight coarse knurl is cut into the reduced diameter portion of the hub, and a chamfer is cut around both ends of the circular center bore of the impeller disc. To mount the impeller disc on the hub, the knurled section of the hubs reduced diameter portion is pressed into the center bore of the impeller disc and the outer annular edge of the reduced hub portion is swaged into the adjacent chamfer to hold the disc solidly against the shoulder on the hub.

DESCRIPTION OF DRAWING FIG. 1 illustrates a disc having turbine blades formed about its periphery and an impeller hub in an unassembled relation;

FIG. 2 illustrates the step of pressing the knurled section of the hub into the center opening of the disc;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2 and looking in the direction of the arrows;

FIG. 4 illustrates the step of swaging the end of the hub to lock the disc in place; and

FIG. 5 is an end view taken from the left end of FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, there is illustrated a disc having a plurality of turbine pockets 12 formed about its peripheral edge, and a hub 14 having a reduced diameter 3,734,697 Patented May 22, 1973 portion 16. The disc 10 has a center opening 18 provided with a chamfer 20 formed in both surfaces of disc 10.

The hub 14 is made as an automatic screw machine product. A plurality of longitudinal grooves 22 are cut into the reduced diameter portion 16 adjacent the shoulder 24 to provide a straight coarse knurl section 26. The outer annular end 28 of reduced diameter portion 16 is machined to the depth of grooves 22.

To mount the disc 10 onto the hub 14, the knurled section 26 is pressed into the center opening 18 to cut corresponding grooves 30 in the disc internal diameter, as depicted in FIG. 5, until the inward side of disc 10 abuts against shoulder 24. The result of this pressing step is to provide a good driving bond between the impeller disc 10 and the hub 12, which is as effective as a key or spline without causing an excessive interference fit that would distort the disc 10.

The assembly depicted in FIG. 2 is then placed in a press to swage (FIG. 4) the outer annular edge 28 of hub reduced portion 16 into the chamfer 20 for the purpose of holding the disc 10 rigidly against the shoulder 24 on the hub 14. The die for this swaging operation is a specially designed concentric ring to control the concentricity of the swaged portions 34 with the hub 14. The die I.D. is controlled so that all the metal displaced goes against the impeller disc 10 and not into the bore of the hub, as would be the case if the end 28 of hub 14 were swaged with a fiat die over its entire end area.

After swaging the resulting composite impeller 36 is put through normal finishing operations to bring it to exact size, FIG. 5 depicts the finished composite impeller mounted on a shaft 40 and fixed thereto by a spline or key 42.

From the foregoing description, it will become apparent that making an impeller by mounting an impeller disc on a hub in accordance with the principles of this invention provides the following advantages:

(1) More flexible inventory.

(2) More simple machine operations.

(3) Ability to make parts in volume using an automatic screw machine which formerly were made in lower quantities by a more expensive chucking machine operation.

While there has been shown and described a preferred embodiment of the present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein Without departing from the spirit and scope of the invention. Although in the description of invention a turbine impeller was used, obviously the method of this invention could be practiced to form any type of impeller, for example, a centrifugal impeller.

What is claimed is:

1. Method of making a pump impeller by afiixing a disc with peripheral blades onto the reduced diameter end portion of a hub, where the diameter of said reduced diameter end portion is slightly greater than a circular bore formed in the center of said impeller disc, comprising the steps of:

(a) forming a chamfer into said disc about one end of said circular bore,

(b) forming a plurality of longitudinal grooves about said reduced hub portion in a lengthwise direction to define a plurality of lengthwise parallel ridges,

(c) pressing said reduced hub portion into the end of said circular bore of said impeller disc opposite to said chamfer to cause said parallel ridges to cut grooves into said impeller disc, and

(d) swaging the outer annular edge of said reduced hub portion into said chamfer to press said impeller disc against the shoulder on said hub defined by the 1 3 4 innerend of said reduced hub portion by using a 1,112,525 10/1914 Darling 29-432 UX concentric ring die to prevent the displacement of 1,988,595 1/ 1935 Hiss 29-156.8 R any metal into the bore of said hub. 2,162,902 6/1939 Adams 29-156.8 R 2. The method of claim 1 wherein said swaging step is 2,750,660 6/1956 Newcomb 29-432 performed around the entire periphery of said outer an- 5 nular edge of said reduced hub portion. I OTHER REFERENCES 3. Themethod of claim 1 wherein said charnfer iforming 15 Ways to Fasten Gears to Sh ft Product Engi step comprises forming a chamfer into said impeller disc nearing, 4 May 30 19 0 about both ends of said circular bore.

10 RICHARD J. HERBST, Primary Examiner D. C. REILLY III, Assistant Examiner References Cited UNITED STATES PATENTS 2,119,334 5/1938 Leffler 29 432 UX US. Cl. X.R. 1,415,542 5/1922 Fuegel et a1 29 522 UX 2 1,157,666 10/1915 Bennett 29 432 X 15 9 156's 156's 525 

